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Cellular Biochemistry > Chapter 10 > Flashcards

Chapter 10 Flashcards

1
Q

Caffeine is antagonist for ____ receptor

A

adenosine

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2
Q

Bacterial Quorum Sensing

A

Sense # organisms in population.

Diffuse through cell membrane, bind to intracellular receptors, effect change in gene receptors

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3
Q

What do kinases do?

A

Gene expression and metabolic activity

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4
Q

limits of signaling (6)

A
  1. amplified intracellularly (stepwise)
  2. regulation
  3. location: cytosol/nuclear
  4. branching: redundancy/cancellation
  5. signal termination (2nd messengers short lived)
  6. desensitization
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5
Q

PKA

A

Ser/Thr kinase

Activation up when phosphorylated (phospho-Thr)
When activated,
Phospho-Thr —-> Arg (+, arginine)

Asp (-, asparagine) near 3rd phosphate and substrate

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6
Q

What 2 things activate PKA?

A

Allosteric activation by cAMP

Priming phospho-thr

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7
Q

Insulin effects

A

increases glycogen synthesis
decreases phosphorylation

opposite PKA, PKA gives fuel mobilization signal

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8
Q

Arrestin

A

Docking protein. When GPCR bound, kinase phosphorylates it. Arrestin recognizes phosphorylated form of G protein.

G protein docking and thus the signal

Arrestin removed by dephosphorylated.

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9
Q

Where is PIP2 cleaved?

A

C3

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10
Q

What does IP3 activate?

A

Calcium released –> PKB/Akt

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11
Q

What does DAG activate?

A

PKC

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12
Q

What 2 things activate PKC?

A

Requires priming at Thr?

DAG causes dock near membrane and conformation change

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13
Q

Calmodulin

A

Regulates calcium
Activates or inhibits target proteins

Bends in 1/2 to grasp target

Binds 2x calcium ions

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14
Q

Cross-Talk between signaling pathways (due to intracellular components) name examples

A

PLC activated by PTKs lipid phosphatases

Sphingomyelinases release sphingosine & ceramide (activate 2nd messengers)

Ceramide = 2nd messenger

Sphingosine-1-phosphate= intra/extracellular signal (-PLC, +GPCRs, aker export by ABC transport) must be exported by ABC but then can diffuse to modify GPCRs

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15
Q

Ras Pathway

A
  1. RTK+ Ras* GDP inactive
  2. Ligand binds, RTK phosphorylates
  3. Adaptor proteins connect Ras to RTK/phosphates
  4. Induced Ras to release GDP and bind to GTP
  5. Activates Kinase
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16
Q

What does Ras target?

A

Nuclear proteins, which alter gene expression= transcription factors

17
Q

What limits Ras signaling

A

GTPase activity

18
Q

What reverses kinase effects ?

A

phosphatases

19
Q

Anticancer drugs

A

inhibit kinases, stop uninhibited growth

20
Q

In lipid hormone signaling, ___ binds to DNA and initiates transcription.

A

Hormone responsive element (HRE)

21
Q

What eicosanoid signaling molecule enzyme converts arachnodonate to prostaglandin H2.

A

Cyclooxygenase

22
Q

Eicosanoids produced when ________activated by phosphorylation and by presence of Ca2+.

A

phospholipase A2

23
Q

Why is ligand binding reversible

A

non-covalent

24
Q

Kinase

A

enzyme that transfers a phosphoryl group from ATP to another molecule.

25
Q

GPCR structure

A

7 transmembrane alpha helices
Pal @ cys

Ligand binding: helical core and extracellular loops

26
Q

Beta blockers

A

Block beta2-Aderngic

Treat high bp

27
Q

how does intrinsic GTPase activity limit a G protein?

A

Bound GTP — > GDP

28
Q

____ is allosteric activator of kinase

A

cAMP

29
Q

When threonine on PKA not phosphorylated,

A

active site blocked

30
Q

Arrestin has ___ residues which bind to phosphoryl group.

A

Lys (+) and Arg (arginine, +)

Arrestin uses endocytosis

31
Q

What changes loop blocking PKC active site?

A

noncovalent binding with DAG

32
Q

Phosphoinositide signaling pathway regulation:

A
  1. Lipid phosphatases: remove phosphoryl groups from PIP2

2. Sphingosine inhibits PLC (see above)

33
Q

What stops Ras signaling?

A

Proteins that enhance GTPase activity so it returns to inactive GDP bound form
Phosphatases reverse some kinases.
Tyrosine kinases can cross-talk (see book for additional notes)

34
Q

Lipids carried in bloodstream by specific carrier protein or ___, all purpose binding protein.

A

albumin

35
Q

Lipid Receptor

A

2 zinc fingers: cross links formed by 4 cysteine residues interacting with 4 zinc ions.

36
Q

Once lipid ligand binds, moves to ____ and binds to HRE, which all have ____

A

nucleus

6-bp sequences separated by a few bp

37
Q

Are lipid signals long lasting?

A

no short range, degraded quickly because unstable and hydrophobic

Cellular Biochemistry (15 decks)

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